This invention relates to needle protector devices and assemblies.
When a catheter is inserted in a vein or similar part of the body, this is often performed using a needle inserted within the catheter. The patient end of the needle is sharp and protrudes from the patient end of the catheter. The patient end of the assembly of the catheter on the needle is inserted in the vein and the needle is subsequently removed, leaving the catheter in position. The needle may be removed through a self-sealing port at the machine end of the catheter; a separate port is used to provide fluid access to the vein. Such an assembly is described, for example, in GB 2088215.
After the needle has been removed from the catheter, its patient end will carry traces of blood, which presents a potential contamination risk to the clinician and to people subsequently handling the needle. In order to protect the tip of the needle from contact after it has been withdrawn from the catheter, it has been proposed that the needle be withdrawn into a tubular protector after use, in the manner described in EP 545671 and EP 734272. In U.S. Pat. No. 4,978,344 there is described a tethered protective cap frictionally retained in a catheter hub so that it is pulled off the catheter and retained with the needle when the needle is pulled out of the catheter hub. Various other devices for protecting the tip of a needle when it is withdrawn from a catheter are described in, for example, U.S. Pat. No. 4,834,718, U.S. Pat No. 5,300,045, EP 799626, U.S. Pat. No. 4,944,725, EP 747083, U.S. Pat. No. 5,718,688 and GB2324734. These arrangements can suffer from various problems. For example, when the device is clamped onto the catheter hub by a member that engages the needle, so that removal of the needle releases the engagement with the hub, this can cause a high frictional force on the needle. Difficulties are also experienced in making practical devices that are effective but do not require close tolerances and costly manufacture.
It is an object of the present invention to provide an improved catheter assembly.
According to one aspect of the present invention there is provided a needle protector device for protecting the tip of a needle after withdrawal of the needle from a catheter, the needle protector device including resilient means for locking with the hub of the catheter, first and second catch members engageable with one another to retain the locking means in engagement with the hub, trigger means arranged to engage the needle such that the trigger means is displaced from a first position when the needle projects into the catheter to a second position when the needle is withdrawn from the catheter, the trigger means being arranged to cooperate with the catch members such that the catch members are retained in engagement with one another when the trigger means is in the first position and can disengage from one another when the trigger means is in the second position.
The resilient means preferably includes two locking arms urged resiliently outwardly away from one another, the catch members being mounted with the arms. Each locking arm may have a hook portion towards one end arranged to engage a projection on the hub of the catheter when the arms are held inwardly. Each locking arm may have an inwardly-projecting member, the catch members being mounted with respective ones of the inwardly-projecting members. One of the inwardly-projecting members preferably has an aperture through which the needle projects when the needle extends in the catheter. The needle protector device is preferably arranged to prevent the needle being extended after it has been withdrawn. The aperture on the one inwardly-projecting member may be displaced out of alignment with the needle when the needle is withdrawn from the catheter. One of the inwardly-projecting members may be urged resiliently away from the other and be held against the other by the trigger means. The trigger means preferably includes a generally longitudinally-extending member urged resiliently laterally against the side of the needle. The needle protector is preferably made as a one-piece plastics molding.
According to another aspect of the present invention there is provided a needle assembly for use with a catheter, the needle assembly including a needle shaft, an elongate protective housing, a slider mounted with the machine end of the needle shaft and slidable along the housing from a first position in which the patient end of the shaft protrudes from the housing to a second position in which the patient end of the shaft is protected within the housing, and a needle protector device according to the above one aspect of the invention located at the patient end of the housing, such that the needle protector device retains the needle assembly with the catheter when the needle extends within the catheter and disengages the needle assembly from the catheter when the needle is withdrawn into the protective housing.